Civil Engineering and Architecture 12(2): 1165-1179, 2024 http://www.hrpub.org DOI: 10.13189/cea.2024.120235 Study on Site Effect in Nanning City Using HVSR Method Hongcheng Ma 1,* , Boi-Yee Liao 2 1 Department of Engineering, International College, Krirk University, Thailand 2 Graduate Program of Engineering Technology Management, International College, Krirk University, Thailand Received August 8, 2023; Revised October 30, 2023; Accepted December 5, 2023 Cite This Paper in the Following Citation Styles (a): [1] Hongcheng Ma, Boi-Yee Liao , "Study on Site Effect in Nanning City Using HVSR Method," Civil Engineering and Architecture, Vol. 12, No. 2, pp. 1165 - 1179, 2024. DOI: 10.13189/cea.2024.120235. (b): Hongcheng Ma, Boi-Yee Liao (2024). Study on Site Effect in Nanning City Using HVSR Method. Civil Engineering and Architecture, 12(2), 1165 - 1179. DOI: 10.13189/cea.2024.120235. Copyright©2024 by authors, all rights reserved. Authors agree that this article remains permanently open access under the terms of the Creative Commons Attribution License 4.0 International License Abstract In order to obtain the site effects and sedimentary layer distribution in Nanning urban area, background noise observation was carried out in Nanning urban area from mid-2022 to early 2023. Using the ground pulsation observation records of 561 points with a distance of 500m in Nanning urban area, the distribution results of resonance frequency and magnification of site effects were obtained by HVSR method, and the sedimentary layer distribution in Nanning urban area was obtained by using the resonance frequency-sedimentary layer thickness conversion formula. In this work, the resonance frequency and amplification factor are comprehensively considered, and the K value distribution characterizing the damage degree of the site in Nanning Urban Area is obtained. The results show that the resonance frequency of Nanning urban area is 1~10Hz, and most areas are mainly concentrated in 1Hz; the thickness of Sedimentary Layer is smaller as a whole, mostly 10 ~ 40m, and some local areas are thicker, up to 40 ~ 100m; its overall damage degree is low, and very few areas exceed the safe value (K > 20), indicating that it is safe in earthquake disasters. The results are consistent with the surface topography and public borehole data, and can provide a basic reference for the expansion of the whole urban project and disaster prevention and reduction. Keywords Nanning Urban Area, HVSR Method, Site Effect, Sedimentary Layer Distribution, Background Noise 1. Introduction According to the relevant research on earthquakes at home and abroad, the main factors that affect ground motion are: the source effect of source and rupture process, the path effect of seismic wave transmission, and the site effects caused by local address characteristics of seismic wave. The damage degree of an earthquake disaster is often closely related to local site effects, and the disaster caused by an earthquake in soft sedimentary site is much more serious than that in a bedrock site. This is especially disadvantageous to most urban areas built on sedimentary soil and thick aquifers such as river valleys, Piedmont alluvial fans and coastal plains to ensure adequate water supply. With a highly developed economy, a highly dense population and the accelerating pace of social urbanization, the occurrence of earthquakes will inevitably cause unimaginable losses. The 1994 Northridge earthquake in Los Angeles, USA, and the 1995 Hanshin M6.8 earthquake occurred at the foot of modern metropolises, causing considerable damage to these cities, while the 1985 M8.1 earthquake outside 400km from Mexico City brought merciless damage to Mexico City, which was built on a thick sedimentary layer around 2.5km. Since then, the study of site effects (i.e., the amplification effect of ground motion by soft sedimentary layers on the surface) has attracted widespread attention. These tips are important for conducting site response assessments and taking precautions before an earthquake strikes.